US5439595A - Water decontamination method using peroxide photolysis ionizer - Google Patents

Abstract

Apparatus and a method are disclosed for decontaminating water, using an ionizing reactor. Water contaminated by organic compounds is introduced into a chamber in which it is concurrently irradiated by microwave and an ultraviolet source to activate it by photolysis. The water is then introduced to a hydroxyl reactor chamber. An oxidizing reagent, such as hydrogen peroxide, is irradiated by subjecting it to the UV source and conducting it through the chamber, without mixing it with the water. The activated water and irradiated oxidizing reagent are then vectored to a locus at which they are mixed under UV from the source. The apparatus and method may be incorporated into a water treatment system employing existing contaminant extraction techniques, such as immiscible fluids separation and turbo-aspirated sparging.

Description

BACKGROUND OF THE INVENTION

This invention relates to a water treatment method and an apparatus, and more particularly, to a method and apparatus for the removal from aqueous fluid of toxic and potentially hazardous organic compounds. The present method and apparatus exploit, synergistically, ultraviolet photolysis, the use of hydroxyl radicals, and microwave energy to, optimize the oxidation of organic contaminants in water.

The use of ultraviolet light and oxidants, such as ozone and hydrogen peroxide, to produce hydroxyl radicals, is well-known. Such a technique has been used to enhance oxidation of organic contaminants in industrial waste water, groundwater and other aqueous solutions. Direct photolysis of organic compounds by intense ultraviolet light is also well known and is used extensively in the water treatment industry. Microwave radiation (electromagnetic waves having a wavelength between about 0.3 and 30 centimeters) is commonly used to induce rapid heating of materials from within by oscillatory stimulation of hydrogen and nitrogen atoms within water and organic molecules. Oxidation of organic contaminants by ultraviolet light or by chemical reaction with hydrogen peroxide ultimately yields innocuous products: carbon dioxide, elemental carbon, water and oxygen.

It has now been found that exploitation of the above techniques in a single compact apparatus creates a potent oxidative water treatment method.

Existing apparatus and methods, using ultraviolet (UV) light and reagents such as hydrogen peroxide to create hydroxyl radicals, are able to treat substantial volumes of water, on the order of hundreds of gallons per minute. In "first generation" systems of this sort, it was proposed that low pressure UV discharge lamps be encased in quartz tubes immersed in tanks of water to be treated. Hydrogen peroxide was added to the water, and the mixture was allowed to flow around the submerged lamps. Problems with rapid fouling of the lamps and low production of hydroxyl radicals in such devices soon became apparent. Second generation apparatus of the above type incorporated manual cleaning mechanisms, and the use of polymer coatings (such as "Teflon" PTFE) on the quartz sleeve, additional oxidizers (such as ozone), and catalyzing additives (such as TiO₂) to enhance the rate of radical production. Lasers also have been used in efforts to increase energy transfer efficiency. Some efforts were successful to some extent, but at the price of significantly greater complexity and cost.

In known prior art apparatus and methods, the oxidizing reagent is added to the water prior to exposure of the mixture to the UV radiation. Since chemical oxidation is rapid, in such arrangements inorganic precipitates quickly form on the quartz sleeve or window surfaces, resulting in immediate and cumulative attenuation of the UV radiation.

Moreover, in known prior art apparatus and methods, addition of the oxidizing reagent to the water prior to UV exposure results in dilution of the reagent, so that the photon density of the UV radiation reaching the oxidant molecules is reduced by preferential absorption by the water, scattering and absorption by entrained particles in the water, and absorption by solutes. Sluggish mixing of the solution during irradiation also minimizes contact of the few radicals that are produced close to the light source, resulting in a relatively inefficient and certainly less than optimal capability for contaminant destruction.

The present invention provides a method and apparatus which addresses and obviates the above shortcomings of the prior art, by synergistically enhancing contaminant destruction by complementary techniques.

SUMMARY OF THE INVENTION

In one of its aspects, the present invention provides, for use in the treatment of waste water, an ionizing reactor for photochemically oxidizing organic compounds in aqueous solutions, using microwave-assisted photolysis and hydroxyl radical oxidation. The photolysis, production of hydroxyl radicals and the final hydroxylation reaction are all effected using a high pressure UV short arc lamp. Peroxide activation is made to take place in such a manner that a pure reagent is continuously irradiated, thus maximizing O₃ and HO₂⁺ and OH⁺ radical production. The reagent, thus activated, is injected into a downstream hydroxylation chamber, where it is mixed in a reaction zone with the pre-sensitized water, still under irradiation. The mixing is made to take place at a paraxial focus, where the ionization kinetics are most aggressive and the principal oxidative destruction of organic compounds occurs. The activated oxidizing reagent, containing free radicals, and the microwave and photosensitized water, are thus mixed vigorously at a point where incident concentrated deep UV radiation irradiates both fluids at once, to enhance the chemical degradation reaction.

Thus, a principal feature of a preferred embodiment of the invention is the simultaneous activation of pure oxidizing reagent with direct UV light and secondary photolysis and sensitization of contaminated water with UV radiation emitted from the walls of tubes (preferably of quartz) which carry the oxidizing reagent, and with microwave radiation from a microwave source (magnetron) positioned to direct high energy electromagnetic waves into the angular path of influent water circulating in a vortex around the tubes.

In its method aspect, the invention contemplates the use of a concentrated beam of deep spectrum ultraviolet light, which is manipulated using an optical array to simultaneously irradiate a reagent such as hydrogen peroxide and to irradiate out of fluid contact with the reagent (and preferably in an environment charged with microwave radiation) water to be treated. The water and the reagent are then mixed vigorously, under continued UV irradiation to optimize oxidation of water-borne contaminants.

A prime advantage of the above-described peroxide photolysis ionizer is that a maximum number of free radicals are produced using one UV source, which is itself safely and efficiently located separate from the reaction chamber. Presensitization of the water by photolysis enhances the ultimate reaction of the contaminants with the free radicals during subsequent hydroxylation.

Because the hydroxylation reaction occurs downstream from any light transmitting or reflecting surfaces, it does not contribute to precipitate fouling of those surfaces, a common problem in the prior art.

As indicated above, all of the fluid to be treated is preferably made to converge at a narrow vertex where a concentrated beam of UV light of optimal wavelength is directed. This minimizes the energy needed to generate free radicals while maximizing the treatment volume capability of the apparatus.

The present invention may be used to good advantage as part of a comprehensive water treatment system in an industrial setting requiring the removal and rapid destruction of recalcitrant contaminants from water, within a minimal space. In one of its embodiments, the present invention may be incorporated into a system comprising a coalescing separator for receiving waste water, a multi-stage turbo-aspiration unit, and one or more peroxide photolysis ionizers of the above-described type associated with the various stages of the turbo-aspiration unit. All of the above components, it has been found, can be mounted on the chassis of a small truck or trailer for portability.

BRIEF DESCRIPTION OF THE DRAWINGS

There are seen in the drawings forms of the invention which are presently preferred (and which constitute the best mode contemplated for carrying the invention into effect), but it should be understood that the invention is not limited to the precise arrangements and instrumentalities shown.

FIG. 1 is a side elevation view, in cross section, of a chamber assembly of the peroxide photolysis ionizer of the present invention;

FIG. 2 is a front elevation view, in cross section, of an arc lamp and associated fiber optic transmission bundles for use in the present invention;

FIG. 3 is a plan view of a ringjet water flow control ring used in the invention;

FIG. 4 is a cross-sectional view of the ringjet water flow control ring shown in FIG. 3, taken along theline 4--4 in FIG. 3;

FIG. 5 is a diagrammatic detail view, illustrating the manner in which the ringjet water flow control ring controls the volume of water flow in apparatus in accordance with the invention;

FIG. 6 is a detail view, in side elevation, illustrating a vernier control element for the ringjet flow control ring;

FIG. 6a is an end elevation view of the vernier control depicted in FIG. 6, showing the manner in which the control element cooperates with the ringjet flow control ring.

FIG. 7 is a side elevation view of a photolysis chamber in accordance with the invention;

FIG. 8 is a top view of a photolysis chamber in accordance with the invention;

FIG. 9 is an end view, in cross-section, taken along theline 9--9 in FIG. 1; and

FIG. 10 is a flow diagram of a water treatment system in accordance with the invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings in detail, wherein like elements are designated by like reference numerals, there is seen in FIG. 1 an ionizing reactor, designated generally by thereference numeral 10. Thereactor 10 comprises, in general, a photolysis chamber assembly, designated generally by thereference numeral 12, and a hydroxyl reactor chamber, designated generally by thereference numeral 14.

Referring now to FIGS. 7 and 8 in addition to FIG. 1, thephotolysis chamber assembly 12 consists, in the illustrated embodiment, of a generally elongatedcylindrical shell 16, preferably of stainless steel. Associated with theshell 16 is awater injection port 18. As is perhaps best seen in FIGS. 7 and 8, theport 18 is so arranged and orientated with respect to the longitudinal axis "A" of theshell 16 that a stream of water flowing through theport 18 will impinge on the curvedinterior wall 20 of theshell 16 and assume a helical or volute path, designated diagrammatically in FIG. 7 as "V". Referring now to FIG. 8, it will be seen that in a transverse cross-sectional view, theport 18 enters tangentially with respect to the circular cross-section of theshell 16. Referring to FIG. 7, it will be seen that the longitudinal axis "B" of thewater port 18 is oblique with respect to the axis "A" of theshell 16, thus encouraging development of the desired helical or volute flow of water within theshell 16.

Referring again to FIG. 1, theshell 16 is supported and retained by an end flange 22 (which may also be referred to as an "access flange", and aringjet flange 24, which will be described in greater detail below. Suitable numbers ofassembly rods 26 join theend flange 22 andringjet flange 24 at locations around their respective peripheries. Therods 26 serve to retain respective ends of theshell 16 inperipheral seats 28 and 30 in theend flange 22 andringjet flange 24, respectively.

Referring again to FIG. 1, associated with theringjet flange 24 within theshell 16 when thephotolysis chamber assembly 12 is assembled, is ahyperbolic reflector body 32, with a quadratic surface, shaped to direct radiation within theshell 16 for maximum effect. Thereflector body 32 is preferably fabricated of highly polished aluminum, sputter-coated with sapphire to provide abrasion and corrosion protection and to optimize spectral reflectivity. Bolts 34 secure thereflector 32 to theringjet flange 24.

Also associated with theringjet flange 24 is a flow control ring 36 (seen in detail in FIG. 3 and 4 and described below), and a vernier control 38 (also discussed below) for theflow control ring 36.

Secured to theringjet flange 24, as bybolts 40, is a tubularhydroxyl reactor chamber 14, which includes awater outlet port 44. Asuitable gasket 42 is disposed between thereactor chamber 14 and theringjet flange 24.

Other aspects of the ionizingreactor 10 will now be described in detail.

Associated with theshell 16, at a position generally juxtaposed to thewater port 18, is amagnetron 46. Themagnetron 46 is associated with a microwave-transparent "window" 48, which enables microwave radiation produced by themagnetron 46 to enter theshell 16 and impinge upon water entering theshell 16 through theport 18. A coolingfan 49 or other suitable cooling arrangement may be provided for the magnetron.

Associated with theaccess flange 22 arequartz tubes 50, 52 and 54. The quartz tubes 50-54 extend, as is seen in FIGS. 1 and 9, into association with theringjet flange 24, and include, in the vicinity of theringjet flange 24, tapered nozzle ends 56. Jam nuts 58, with suitable gasket features, secure the upper ends of the quartz tubes 50-54 to theaccess flange 22. Associated with the upper ends of the quartz tubes 50-54 are T-fittings, of which the T-fitting 60 associated with thequartz tube 54 is typical. The T-fitting 60 provides aninlet 62 for reagent, as well as acoupling 64 to facilitate attachment of a reagent supply conduit 66. The quartz tubes 50-54 traverse the length of thephotolysis chamber 12, in a direction parallel to the axis "A".

Also associated with the quartz tubes 50-54 are fiber optic sources, of which the illustratedsource 68, a fiber optic conductor, may be considered typical. Thefiber optic conductors 68 are coupled to the respective quartz tubes, such as thequartz tube 52, by fiber optic couplers, such as thecoupler 70, and the upper ends of the quartz tubes 50-54 are sealed at the couplers by quartz windows, such as illustratedquartz window 72 associated with thetube 54. Theconductors 68 are preferably of the high deep UV transmission fluid-filled type.

It will now be apparent that hydrogen peroxide introduced to the quartz tubes 50-54 through supply conduits, such as the conduit 66, will flow the length of the quartz tubes 50-54 and thephotolysis chamber 12, to emerge at the nozzle ends 56 of the quartz tubes 50-54.

Referring now to FIG. 2, an exemplary ultraviolet source is seen. The illustrated source provides anarc lamp 76, disposed within anellipsoidal reflector 78, both within ahousing 80. A trifurcatedoptic collector 82 is juxtaposed to thereflector 78 and associated with respective ends of fiber optic conductors such as the above-described fiberoptic conductor 68. It will be understood that eachfiber optic conductor 68 is associated with one of the quartz tubes 50-54. Across-slide mechanism 84, associated with thehousing 80 andarc lamp 76, provides for focus and alignment adjustments for the arc lamp. Any suitable mechanism may be used for incremental adjustment of the position of thearc lamp 76. Suitable adjustment wheels or knobs 86 (for arc lamp alignment) and 88 (for focus) are provided. The arc lamp may be a 350 watt high pressure short arc mercury-xenon lamp, of the kind presently commercially available from Advanced Radiation Corp., Ushio Corp. and Ultra Violet Products, among others.

The application of UV radiation to the quartz tubes 50-54 in the above manner results in irradiation of the hydrogen peroxide flowing through the tubes 50-54, and, by Lambertian diffusion, irradiation of thephotolysis chamber 12. Thechamber 12 is preferably also simultaneously subjected to microwave radiation produced by themagnetron 46, so that water in thephotolysis chamber 12 is irradiated and sensitized by the concurrent microwave and UV photon impingement. The peroxide reagent is continuously activated by direct UV radiation during its internal course along the length of the tubes 50-54. The reagent also serves as a light pipe, conducting UV radiation to thehydroxyl reactor chamber 14.

Referring now to FIGS. 3, 4 and 9, the manner in which activated reagent and sensitized water are directed to a paraxial focus point in the hydroxyl reactor chamber 14 (where conducted UV radiation traveling axiality through the reagent also impinges on the fluids) which will now be described. It will be understood that the principal oxidation reaction produced by thereactor 10 occurs at this locus, and may be further enhanced by mixing in a downstream turbo-aspirated sparging apparatus, as will be described below.

Referring now to FIGS. 1, 3, 4 and 9, theringjet flange 24 is provided with a circular array of water orifices 90 (twelve in the illustrated embodiment), extending through the ringjet flange at a preferred angle of 20° with respect to the longitudinal axis "A" of thehydroxyl reactor chamber 14. The illustratedorifices 90 are evenly distributed around the periphery of theringjet flange 24, and at the same radial distance from the center of the ringjet flange. As is seen in FIG. 1, the respective longitudinal center lines "L" of theorifices 90 converge at a locus (or focal point) "F". The activated oxidizing reagent (hydrogen peroxide) emerging from the tubes 50-54 exits from the nozzle ends 56 into thehydroxyl reactor chamber 24 at the positions perhaps best seen in FIGS. 1 and 9. The reagent exits within the circle of theorifices 90, and into a zone adjacent the locus or focal point "F", where the activated oxidizing reagent containing free radicals and the microwaved and photosensitized water are mixed. The UV radiation conducted by the reagent in the quartz tubes 50-54 is likewise transmitted to thehydroxyl reactor chamber 14, where the incident concentrated radiation continues the irradiation of both fluids as mixing occurs.

The manner in which the rate of water flow between thephotolysis chamber 12 andhydroxyl reactor chamber 14 may be controlled will now be described.

Referring to FIG. 1, theringjet flange 24 has in one of its surfaces acircular recess 94. Theflow control ring 36 is also circular, and has an outer diameter which allows it to be received in therecess 94. Referring to FIG. 5, theflow control ring 36 has a central clearance opening and an array oforifices 98, corresponding in number to the number oforifices 90 of theringjet flange 24. Theorifices 98 extend through theflow control ring 36 at an angle corresponding to the angle of theorifices 90 of the ring jet flange 24 (here 20°). Theorifices 98 of theflow control ring 36 are disposed at the same radial distance from the center of theflow control ring 36, that distance being selected so that theorifices 98, when aligned with theorifices 90, form respective continuous passages of circular cross section.

Referring now to FIG. 3, it will be seen that theflow control ring 36 has aperipheral edge 100, interrupted at one point by a radially directeddrive slot 102. Referring to FIG. 1, thevernier control 38 is mounted in theringjet flange 24. Thevernier control 38 has an eccentricallymounted drive pin 104, which projects into the drive slot 102 (as is perhaps best seen in FIGS. 1 and 6a). Rotation, therefore, of thevernier control 38 causes thedrive pin 104 to rotate theflow control ring 36 relative to the ringjet flange as thepin 104 traverses the height of theslot 102. Rotation of theflow control ring 36 relative to theringjet flange 24 causes offset of theorifices 90 and 98, as seen for example in FIG. 5, and consequent reduction of the flow area provided by the orifices. Thus, the total area of the orifices available for transfer of water between thechambers 12 and 14, and hence the flow volume and velocity, may be finely adjusted.

FIG. 10 illustrates a water treatment system in accordance with the invention, in which the above-ionizing reactor cooperates with a number of known components assembled in a unique manner, to provide efficient treatment of contaminated water. Referring now to FIG. 10, the system, designated generally by thereference numeral 106, includes a coalescingseparator 108, into which influent is introduced at 110. Heavy sediments and immiscible fluids are mechanically separated from the influent and removed at thesediment drain 112. Lighter contaminants, such as hydrocarbons in the liquid phase, are drawn off at aconduit 114 to a collection andstorage drum 116. The remaining water, still containing organic contaminants, is withdrawn from theseparator 108 through theconduit 118, and pumped as input into a tubro-aspiratedsparger 120. Off gas from the sparger is removed through a manifold 122, and the water output of the sparger is directed and pumped to thewater inlet port 18 of anionizing reactor 10. Oxidizing reagent, such as hydrogen peroxide, is provided to thereactor 10 from astorage drum 124, by means of ametering pump 126 andconduit 128.

The effluent from the ionizingreactor 10 is introduced into asecond sparger 130, whose off gasses are drawn off into themanifold 122. The efflux from thesparger 130 is pumped through aconduit 132 to a third sparger 134 (also associated with the manifold 122), and from thethird sparger 134 through aconduit 136 to a fourth sparger 138 (also associated with the manifold 122). Clean water is discharged from thesparger 138 at a conduit 140. Anaspirator 142 may advantageously be associated with eachsparger 120, 130, 134 and 138.

It will be appreciated that, although four spargers (and thus four sparging stages ) are shown, the present invention may be used with other numbers of sparging stages. Various commercially available sparging units are suitable for use in the above-described system.

The present invention may be embodied in other specific forms without departing from its spirit or essential attributes. Accordingly, reference should be made to the appended claims, rather than the foregoing specification, as indicating the scope of the invention.

Claims (6)

I claim:

1. A method for the removal of contaminants from water, comprising the steps of:

a. providing a first and a second reaction chamber and a source of ultraviolet radiation operatively associated therewith;

b. introducing into the first reaction chamber a stream of water;

c. providing a stream of oxidizing reagent out of fluid contact with the stream of water;

d. simultaneously subjecting the water and the oxidizing reagent to the ultraviolet radiation to irradiate them and hydrolyze the reagent;

e. introducing the irradiated water and hydrolyzed reagent to the second reaction chamber; and

f. mixing the water and the reagent in the second chamber while subjecting the water and the reagent to ultraviolet radiation from the source.

2. A method in accordance with claim 1, and the further step of:

g. subjecting the water in the first reaction chamber to microwave radiation while conducting said step of subjecting the water and the oxidizing reagent to the ultraviolet radiation.

3. A method in accordance with claim 2, wherein said step b. is so conducted as to direct the stream of water into helical flow within the first reaction chamber.

4. A method in accordance with claim 2, wherein said step e. comprises the further step of:

h. directing the water and the reagent to a focal zone.

5. A method in accordance with claim 1, wherein said step d. and said step f. comprise the further steps of:

i. providing in the first chamber a plurality of light-conducting tubular members;

j. so conducting said step c. that said stream of oxidizing reagent is made to flow through the tubular members; and

k. conducting ultraviolet radiation from said source to respective ends of said tubular members, whereby scattering of ultraviolet radiation from said tubular members irradiates the water and the reagent in accordance with said step d., and radiation conducted by the tubular members and the reagent subjects the water and reagent in the second chamber to ultraviolet radiation from the source in accordance with said step f.

6. A method for the removal of contaminants from water, comprising the steps of:

a. providing a first and a second reaction chamber and a source of ultraviolet radiation operatively associated therewith;

b. introducing into the first reaction chamber a stream of water;

c. providing a stream of oxidizing reagent and passing the stream of oxidizing reagent through the first reaction chamber out of fluid contact with the stream of water;

d. simultaneously subjecting the water and the oxidizing reagent to the ultraviolet radiation to irradiate them and hydrolyze the reagent;

e. introducing the irradiated water and hydrolyzed reagent to the second reaction chamber; and

f. mixing the water and the reagent in the second chamber while subjecting the water and the reagent to ultraviolet radiation from the source.

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